In a conventional technique, the monitoring functions of “sFlow”, “RSPAN (Remote switched Port Analyzer)” and so on exist in each of switches of a switch system. For this reason, each switch can perform the monitoring, but it was difficult to perform the centralized control of the monitoring functions.
Although there is a function such as “sFlow” in which the centralized control can be applied, there are many constraints that each switch needs to be configured and the grain degree of the monitoring itself is limited, so that there is no degree of freedom to the centralized control of the monitoring.
Also, even if the centralized control can be applied to the function, the function is only the centralized control of the monitoring, and the routing control cannot be coupled with the function. Therefore, the grain degree of the monitoring cannot be changed based on the monitoring result and the monitoring result cannot be reflected on the routing control of the network.
At present, the routing control using the open flow (OpenFlow) technique for the control protocol of the transmitter device has been studied as one of the routing control techniques of the network communication. The details of the open flow technique are described in Non-Patent Literatures 1 and 2. The routing control using the open flow technique is called an open flow network.
In the open flow network, a controller such as an OFC (OpenFlow controller) controls the behavior of the switch such as an OFS (OpenFlow switch) by manipulating the flow table (Flow Table) of the switch. The controller and the switch are connected by a secure channel for the controller to control the switch by using an open flow protocol based control message.
The switches in the open flow network configure an open flow network, and are edge switches and core switches which are under the control of the controller. A series of operations from the reception of a packet (communication data) by an input side edge switch to the transmission of the packet from an output side edge switch in the open flow network is called a flow.
A flow table is a table in which a flow entry is registered to define a predetermined action (predetermined processing) to be performed on a packet group (a packet sequence) hit or adapted to a predetermined rule (a match condition).
The rule of the flow entry is defined or distinguished based on any one or all of a destination address, a source address, a destination port, and a source port, which are contained in a header region of the packet for each protocol layer. It should be noted that the addresses contains a MAC address (Media Access Control Address) and IP address (Internet Protocol Address). Also, the data of an ingress port in addition to the above can be used as the rule of the flow entry.
The action of the flow entry shows operation such as “outputting at a specific port”, “discarding”, “rewriting a header”. For example, the switch outputs a packet to the port corresponding to the action when identification data of the output port (output port number and so on) is shown in the action of the flow entry, and discards the packet when the identification data of the output port is not shown. Or, the switch rewrites the header of the packet based on header data when the header data is shown by the action of the flow entry.
The switch in the open flow network executes the action of the flow entry to the packet group hitting the rule of the flow entry registered on the flow table.
In the control system using the open flow technique, it is possible to monitor the communication by acquiring the statistic data every flow entry.
However, in the control system using the open flow technique as it is, the statistic data has a one-to-one relation to the routing control entry of the flow. Accordingly, the grain degree of the monitoring needs to be set while being is conscious of the routing control entry of the flow.